The invention relates to measuring of pressure and pressure drop in a patients nose (rhinomanometry).
In the present application the anatomic references have the following meaning:
Nostril: each of the two openings of the nose towards the surroundings, as well as the immediately inside the openings located part of the nose cavities;
Nose cavity: each of the two cavities between the (Septum Nasi) to the rear edge of the nose separation;
Nose separation (Septum Nasi): the separation that separates the two nose cavities;
Cavity behind the rear edge of the nose separation (epipharynx): the cavity located behind the nose separation rear edge and which constitutes the transition between the nose cavities and the throat;
oropharynx: the cavity from the soft plate and down to the branching of the opening (trachea) and the gullet (oesophagus).
Eustachian tube (Tuba): the canal extending from the cavity behind the rear edge of the nose separation of the middle ear.
Rhinomanometry is known examination method for examining flow resistances in the nose. By Rhinomanometry the pressure drop is measured created over each nostril and related nose cavity to (epipharynx) when breathing in and/or out.
These examinations can be active as well as passive (i.e. with or without the patients co-operation, respectively), where the active one has been the most commonly used.
In order to determine the flow resistance over a nostril with related nose cavity it is necessary to determine the pressure difference created from the nostril opening to epipharynx the rear edge of the nose separation (septum nasi) during breathing in or out, simultaneously with the corresponding air flow.
The examination can typically be performed by that the patient breathes via a nose mask or through a measuring tube mounted directly on the one nostril. In the mask, or measuring tube, respectively an apparatus is located which is able to measure the airflow during breathing in or out. The flow measurement can be performed in numerous ways, e.g. as the pressure drop over a known orifice plate or implicitly as the temperature of a heated wire cooled by the airflow.
Rhinomanometry is through the recent more than 25 years typically performed in the following manner for each of the patient""s nostrils:
A so-called rhinomanometer comprising a mask with a flow measuring tube mounted thereon is mounted on the nose and a pressure difference transducer in the tube register the pressure drop over an orifice plate, i.e. between the surrounding atmosphere and the inside of the flow tube. The pressure drop created over the orifice plate is hereby an expression for the actual flow. The one side of a second pressure difference transducer opens into the flow measuring tube and its other side opens into a tube, through which the pressure at the rear edge of the nose separation is to be measured.
The pressure at this location (the reference pressure) can be measured through the nostril where flow is not measured via a measuring tube snugly connected to the nostril. Hereby the nose cavity, wherein there is no flow, (and the cavity not occluded by secretion) for determining the pressure at the rear edge of the nose separation to (epipharynx)
This of course has its limitations, as the opposite nose cavity cannot be used as a measuring canal if it is totally or partly clogged.
Alternatively the measuring canal can be established through the mouth, but the pressure in the mouth is only equal to the pressure in the cavity behind the rear edge of the nose separation to (epipharynx), when the soft palate as well as the tongue root (the rear part of the tongue) are in lowered positions, where there is an open passage from the mouth and the throat to epipharynx.
Experience has however shown that it cannot be realized to obtain reliable measurements of the reference pressure through the mouth, as the conditions for doing this is that the patient as mentioned maintains an open passage from the mouth and the throat to epipharynx (by means of the tongue root). By evaluations of it has been concluded that at about 30% of the measurements performed through the mouth, the patient unwillingly closes the passage between the mouth, and the throat to epipharynx, resulting in that these 30% are without value, following the erroneous measurement of the pressure behind the rear edge of the nose separation, where the examiner is not aware of the error.
Furthermore it is a major disadvantage at the hitherto known rhinomanometry examination methods that the function of the Eustachian tubes cannot be monitored. Problems with increased flow resistance in the nose often is connected with problems in the middle ear or with problems in the cavity behind the rear edge of the nose separation (epipharynx), e.g. polyps, which also influence the function of the Eustachian tubes.
It is an objective with the present invention to provide an apparatus, which in different configurations makes far more effective rhinomanometry measurements possible, and which remedies the above mentioned problems and makes possible the measurement of opening pressure for the Eustachian tubes.
By an apparatus for Rhinomanometry and of the type described above, which corresponds to the introductory part of claim 1, the objective is achieved by means of the features mentioned in the characterizing part of claim 1.
By means of these features it is achieved that the apparatus according to the invention can detect whether there is an acoustic connection between those of a patients respiratory and ear passages to which the apparatus is connected, and thereby implicitly whether there is an opening for pressure equalization and/or air flow between the openings.
With the features mentioned in claim 2 it is achieved that it can be monitored whether there is an acoustical connection from the mouth to the nose, and thereby whether there is a pressure equalizing connection from the mouth to the cavity behind the rear edge of the nose separation.
With the features mentioned in claim 3 IT is achieved that it can monitored whether there is an acoustical connection from the nose to the middle ear, and thereby whether there is a pressure equalization connection from the cavity behind the rear edge of the nose separation, through the Eustachian tube to the middle ear.
With the features mentioned in claim 4 it is achieved that the patient himself can establish a pressure in a nose mask or a nose adaptation piece which is connected to the measuring tubes proximal end and thereby built up a pressure in the cavity behind the rear edge of the nose separation, which pressure can provoke the Eustachian tube to open.
With the features mentioned in claim 5 it is achieved that a corresponding pressure can be established from an outer pressure source, which makes it possible that the patient can perform swallowing or chewing movements with a well-defined pressure in the cavity behind the nose separation (epipharynx).
With the features mentioned in claim 6 a corresponding effect is achieved as in connection with claim 2, when the patients second nostril is used as measuring canal, as described above.
With the features mentioned in claim 7 a simplification is achieved, which means that separate microphones are not necessary for sampling the transmitted sound signal. In many rhinomanometers pressure or pressure difference transducers are already present, which have 3 dB crossover frequency at 1 kHz or higher, and which therefore also can measure dynamic pressure changes. Such transducers can immediately be used as microphones, when the sound signal has a frequency of 500 Hz.
With the features mentioned in claim 8 it is achieved in connection with the features mentioned in claim 7 that a known rhinomanometer can be used as an apparatus according to the invention, only adding a battery driven sound generator transducer and one amplifier filter with microphones included related fittings for connection to the relevant tubes of the rhinomanometer.
With the features mentioned in claim 9 a reliable function of the sound signal path in the apparatus according to the invention is achieved, also when relatively high static pressures are present in the patient""s respiratory passages.
With the features mentioned in claim 10 an advantageous and automated process is achieved, which can comprise that the examiner and/or the patient by means of sound signals are made aware of whether the required measuring conditions are present.
The invention also relates to a supplementary apparatus as defined in claim 11. By adding the supplementary apparatus to an existing apparatus the same effect as described above may be obtained. The features described above may, where applicable, be applied to this part of the invention.
It is a second objective of the present invention to provide for the mentioned measurements:
This objective is achieved with the features mentioned in claims 12-17.
With the features mentioned in claim 12 a reliable detecting of whether the patient has lifted the tongue root and/or the soft palate is achieved, and thereby clogged the measuring canal extending through the mouth. When this canal is clogged, the acoustical signal path is simultaneously blocked, which immediately can be detected by the significantly drop in level of the acoustic signal.
With the features mentioned in claim 13 advantages corresponding to those mentioned in connection with claim 10.
With the features mentioned in claim 14 a reliable detecting of whether the passage between the patients second nose cavity and second nostril is clogged.
With the features mentioned in claim 15 advantages corresponding to those mentioned in connection with claim 10.
With the features mentioned in claim 16 a reliable detecting of whether the Eustachian tube is open or closed, which is not possible with the prior art.
With the features mentioned in claim 17 a reliable determining of the opening pressure for the Eustachian tube, which is likewise not possible with the prior art.
It should be appreciated that by the expression sound signal a broad spectrum of sound signals is meant, including infra sound frequencies as well as ultra sound frequencies.